Date of Award

1990

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

The efficient design and maintenance of information retrieval systems are still important considerations, even with the current availability of faster computer hardware and cheaper secondary storage. Informetrics, the quantitative study of information and its use, could provide the systems designer and analyst with tools with which to aid in decision making for optimising system performance.;This study examines how informetrics can be used to help the systems designer in deciding what types of file structures would provide the best performance for a given type of information system environment. It is hypothesized that for varying index term distributions and system term usage patterns, different file structures provide more timely access and require less space.;A factorial design simulation study was carried out to examine the retrieval performance and space requirements of several types of hypothetical information retrieval systems. Performance estimates were based on simulation runs varying system parameters which included the index term distribution, the term selection relationship and number of index terms. Results under different file structures were compared using multi-way Analysis of Variance.;It was found that different structures were better suited for different retrieval environments. The chained hashing structure, in most cases, provided the best retrieval performance and most economical space requirements where gradually decreasing term distributions were present. However, the proposed modified hashing structure performed better in situations where steep term distributions existed. Two variations of the BIM-tree (Balanced Implicit Multiway tree) also provided good performance where steep term distributions were encountered and where the term selection relationship favoured the retrieval of terms with larger postings lists.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.